Toroidal coils are common articles of commerce. They are used as transformers, inductors and chokes in electronic circuits. Forms of toroidal coils have been used as integrating and differential transformers (Butow U.S. Pat. No. 1,866,751, Knopp U.S. Pat. No. 1,141,642), meter probes (Quietzsch et al U.S. Pat. No. 4,100,488, Adams U.S. Pat. No. 3,684,955), for high voltage current measurement (Kashiwa Japanese patent No. 63,264), indicating devices for welding systems (Klemperer, U.S. Pat. No. 2,452,060) and devices for monitoring current wave forms produced by lightning strikes (Wojtasinski et al. U.S. Pat. No. 4,100,487). None, however, has been a self-contained unit.
These prior art devices are no doubt effective for their particular applications, but they tend to be complicated or adapted to a limited particular use.
One of the objects of this invention is to provide a current indicating device which is inexpensive, has a multiplicity of applications, and provides a ready means for determining fault conditions, among other uses.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.